This invention relates to a vacuum insulating glass (IG) unit, and a method of making the same. More particularly, this invention relates to a vacuum IG unit including a peripheral seal including at least one spacer.
Commonly owned U.S. Ser. Nos. 09/303,550 entitled xe2x80x9cVACUUM IG PILLAR WITH DLC COATINGxe2x80x9d filed May 3, 1999 now U.S. Pat. No. 6,326,067; Ser. No. 09/404,659 filed Sep. 24, 1999 entitled xe2x80x9cVACUUM IG WINDOW UNIT WITH PERIPHERAL SEAL AT LEAST PARTIALLY DIFFUSED AT TEMPERxe2x80x9d now U.S. Pat. No. 6,336,989; as well as Ser. Nos. 09/422,244 and 09/416,886 mentioned above, are all hereby incorporated herein by reference.
Vacuum IG units are known in the art. For example, see U.S. Pat. Nos. 5,664,395, 5,657,607, 5,891,536 and 5,902,652, the disclosures of which are all hereby incorporated herein by reference.
Prior art FIGS. 1-2 illustrate a conventional vacuum IG unit 1. IG unit 1 includes two spaced apart sheets of glass 2 and 3 which enclose an evacuated or low pressure space 11 therebetween. Glass sheets 2 and 3 are interconnected by peripheral or edge seal of fused solder glass 4 and an array of support pillars 5.
Pump out tube 6 is sealed by solder glass 7 to an aperture or hole which passes from an interior surface of glass sheet 2 to the bottom of recess 9. Cavity 8 in sheet 3 accommodates the stump of tube 6. A vacuum is attached to tube 6 (prior to the tube being sealed) so that the interior cavity 11 between sheets 2 and 3 can be evacuated to create a low pressure area. After evacuation, tube 6 is melted to seal the vacuum.
As illustrated in FIGS. 1-2, spacers or pillars 5 are typically provided between the glass sheets 2 and 3 through the viewing area of the unit, but not at edges thereof where peripheral or edge seal 4 is located. This results in the thickness of gap or space 11 potentially varying from one thickness near the edge (s) of the glass sheet (s) to a different thickness near the center where more spacers are provided. In other words, there is a potential for substantial undesirable variation near the edges relative to center areas of the unit. If the gap or thickness of the low pressure space 11 between the substrates is lower or higher at an edge than proximate the center of the unit, then the edge seal and/or glass substrate (s) can have higher stress than if the gap is approximately equal throughout the unit. The higher the stress, the more likely it is for either of the glass substrates to crack or break, and the more likely it is for the edge seal to delaminate. Furthermore, this may cause certain pillars 5 to dig into a substrate 2 (or 3) more than other pillars 5 due to stress differences.
It is apparent from the above that there exists a need in the art for a vacuum IG unit, and corresponding method of making the same, designed so as to reduce the potential for significant gap variation between two substrates.
This invention will now be described with respect to certain embodiments thereof, accompanied by certain illustrations.
An object of this invention is to provide a vacuum insulating glass (IG) unit including first and second peripheral or edge seals, and at least one spacer or pillar provided at least partially between the first and second edge seals.
Another object of this invention is to fulfill any and/or all of the above-listed objects and/or needs.
Generally speaking, this invention fulfills any or all of the above described objects or needs in the art by providing a thermally insulating glass panel comprising:
first and second spaced apart glass substrates defining a low pressure space therebetween having a pressure less than atmospheric pressure;
a first plurality of spacers disposed between said first and second glass substrates for spacing said substrates from one another in order to maintain said low pressure space therebetween;
first and second edge seals; and
a second plurality of spacers for spacing said substrates from one another, at least some of said spacers of said second plurality being disposed at least partially between said first and second edge seals.